The present invention is directed to a weightlifting device. More particularly, exemplary embodiments of the present invention are directed to an adjustable weight dumbbell device and system having an internal plate retention mechanism.
Many weightlifters perform a variety of exercises to build and develop muscle. These exercises can be performed through the use of free weights or the use of weightlifting machines. While both free weights and weightlifting machines provide a means to develop and build muscle, many weightlifters prefer the natural motion afforded by the use of free weights, such as dumbbells and barbells. The ability to move naturally allows the weightlifter a greater degree of variety in their exercise routine and the ability to isolate specific muscles.
Although conventional dumbbells provide the freedom desired by weightlifters, conventional dumbbells have several drawbacks. Many conventional dumbbells are made of a cast metal and therefore provide the user with a fixed weight. The fixed weight dumbbells prevent a user from adjusting the amount of weight used, thus decreasing the amount of exercise options available to the user. Other conventional dumbbells are provided with removable weight plates allowing the user to adjust the weight to be lifted. These types of dumbbells may require the clamps, brackets, screws to secure the weight plates to the dumbbell. Although allowing the weight to be adjusted, the attachment devices may be cumbersome and subject to failure potentially injuring the user or others.
Advanced versions of dumbbells and barbells are devices that have attachable weights mounted on a weight lifting bar. In these embodiments, the weights may be prevented from falling from the bar through the use of screws or clamps disposed outside the weights on the bar. These devices are often inconvenient to mount onto the bar and remove from the bar. Each of these mechanisms must be placed separately on the bar. Another drawback of this type of weight lifting system is the expense of purchasing separate pieces of equipment for each different weight desired to be used by the weightlifter.
Even more advanced versions of dumbbells and barbells are devices that allow the user to select a desired amount of weight to be lifted from a stack of weights. However, many of these devices interfere with the natural movement of the user during the lifting motion. These devices force the user to insert a hand into a cage to lift the weight, severely limiting the movement of the user's wrist. These devices may also be cumbersome to use. Although the devices allow a user to select a desired amount of weight, the width of the dumbbell and barbell may be static making the device unstable during use. In addition, these devices offer little in the way of safety.